base quencher

https://doi.org/10.1351/goldbook.09453
Base added to a chemical amplification resist to neutralize low levels of acid that might diffuse into nominally unexposed regions and cause blur.
Source:
PAC, 2020, 92, 1861. (Terminology of polymers in advanced lithography (IUPAC Recommendations 2020)) on page 1868 [Terms] [Paper]